None of the canonical Gospels were written by people who had firsthand knowledge of Jesus. All of them were written over a generation after the crucifixion, and those were only four out of many such Gospels in pre-Biblical Christian history. And none of them (not even the canon) agree on any but the most basic narrative, which you would expect at the very least for eyewitness, firsthand accounts.

Since you seem to be a Christian working from a perspective of faith, I don't expect to convince you of anything, but you should at least study Biblical history a bit[0] before making as naive an argument as this.

>What other response would you expect from someone who actually knew someone who actually died and was brought back to life?

Many people are passionately convinced of things that aren't true. Passion is not a signifier of truth, rather it signifies a willingness to abandon objectivity. You're presenting the common Christian apologetic that the passion of the original Christians and the longevity of the religion is a sign of the validity of the resurrection, as no one would be expected to suffer for a known falsehood. This argument fails to take into account that every religion has its zealots, and people who suffer and die for their faith. That no more validates Christianity than it does the pagan faiths it replaced.

[0]https://en.wikipedia.org/wiki/Historical_reliability_of_the_...